1. Field of the Invention
This invention relates to novel fluorocarbon compounds. More particularly, this invention relates to liquid or waxy cotelomers of chlorotrifluoroethylene and selected perfluorinated ethylenically unsaturated organic compounds, and to a method for stabilizing these cotelomers to yield liquid or waxy materials exhibiting combinations of desirable chemical, thermal and electrical properties that are lacking in many prior art fluorinated telomers and cotelomers of chlorotrifluoroethylene.
2. Description of the Prior Art
The use of chlorotrifluoroethylene telomers as lubricants is disclosed in many patents, such as U.S. Pat. No. 2,770,659. The use of these telomers as hydraulic fluids is also known. The cotelomerization of fluoroolefins is also reported in many patents and papers, e.g., U.S. Pat. Nos. 3,002,031; 3,091,648 and 3,219,712, European Patent Office Publication No. 321,990 and the text "Free Radical Telomerization" by C. M. Starks, published by the Academic Press in 1974.
Specifically, copolymers of chlorotrifluoroethylene and vinylidene fluoride or of tetrafluoroethylene and hexafluoropropene are also disclosed in the prior art.
Irregularities in the orientation of repeating units in telomers derived from chlorotrifluoroethylene, referred to hereinafter as CTFE, results in the presence of chlorine atoms on adjacent carbon atoms. These "tail-to-tail" sequences can occur in 5 to 10% of the repeating units when the temperature of the telomerization exceeds about 120.degree. C. or when some other severe conditions of activation are used to promote the telomerization. The presence of these tail-to tail sequences is believed responsible for the relatively poor thermal stability of these telomers in the presence of oxygen and metals such as iron and its alloys, zinc and aluminum, and the limited capability of these telomers to function effectively and safely as lubricants at high temperatures. These disadvantages are considered due primarily to the ease with which these telomers undergo metal-catalyzed dechlorination of .dbd.ClC--CCl.dbd. groups or to the presence of labile terminal groups such as CFCl.sub.2 that initiate corrosion of the metal.
The decomposition of the telomers is accelerated in the presence of overheated metal surfaces that frequently occur in rotating or reciprocating mechanical devices. The presence of oxygen and water can accelerate the chloride-initiated corrosion of metal. These disadvantages of liquid telomers derived from CTFE have considerably limited the industrial application of these materials.
An objective of this invention is to provide a class of fluorocarbon cotelomers that does not exhibit the aforementioned disadvantages of prior art telomers of chlorotrifluoroethylene.
A second objective of this invention is to provide thermally stable, chemically inert and hydrogen-free cotelomers containing at least 50 weight percent of fluorine and additional elements limited to carbon, chlorine and oxygen.
Another objective of this invention is to provide a method for stabilizing cotelomers of CTFE against heat-induced degradation.